The invention relates generally to control valves. In more specific aspects, the invention relates to: two-way three position type control valves which are particularly useful in remote locations where long signal lines are required, such as is the case with submerged christmas trees used with subsea oil production; and methods for assembling and using the control valves.
Due to cost, most subsea oil and gas wells are produced to, and controlled from, an available offshore host facility. Rarely are new offshore structures constructed unless they are dedicated to several wells. Each well, in most cases, can be miles away from the facility. Control of the wells on such long offsets has been performed using several different methods: direct hydraulic, piloted hydraulic, direct electric, and multiplex electric, just to name a few. In the direct hydraulic method, valves, such as subsea tree valves, are controlled using individual pressurized conduits from the surface hydraulic power unit (xe2x80x9cHPUxe2x80x9d). This method can he used over a short offset but is prohibitive over a longer distance due to the slow response time to open or close a subsea valve. It is also typically limited to control only one or two wells due to the number of conduits required to control each tree. In the piloted hydraulic methodology, control valves are placed locally on the subsea tree and then pilot operated from the surface HPU as to direct a main hydraulic supply to the individual tree valve actuators. This method has a shorter response time due to the fact the hydraulic conduits from the host facility only need to actuate the smaller pilot valves and not the larger tree valves. Although operational distance has been increased using the xe2x80x9cpiloted hydraulicxe2x80x9d method operation of more than a few wells, it is still prohibitive by the number and size of the pressure conduits required in the control link umbilical.
In the direct electric methodology, control valves are placed locally on the subsea tree which are then operated selectively using electrical power from the host facility. Individual conductor sets are dedicated to each valve. The subsea control valves can be operated selectively by a simple switch or Program Logic Controller (xe2x80x9cPLCxe2x80x9d). In addition the PLC can be mounted on and used for control of the HPU, thus increasing the system efficiency. The problem of extended distances are somewhat solved with this method. However, use of the direct electric methodology for more than a few wells is still prohibitive by the number and size of the electrical conductors required in the control link umbilical.
In the multiplex methodology, control valves are placed locally on the subsea tree then operated selectively using an electrical power and signal link from the host facility. The electrical power is sent to the valves, which are then selected for operation by a signal via modem. The number of pressured conduits and electrical conductors are greatly reduced in the control umbilical link to the subsea trees. Many aspects of distance and multi-well control are solved with this method. However, there still exists a need for a control valve system operated over long distances and placed locally, for example, on a subsea tree, operated selectively using electrical power from the host facility and which uses a minimal number of conduits and a minimal amount of power.
The electrically operated control valve may have several configurations depending upon the specific application. The following are a few examples of configurations that may be used. These include a xe2x80x9cpower on activatedxe2x80x9d methodology, a pulse activated methodology, and a failsafe methodology. In the power on activated methodology, the valve will remain open or activated as long as electrical power is applied to an electrical power actuator such as a solenoid coil. When the power is removed the valve will close or deactivate. In the pulse activated methodology, an electrical power pulse is applied to the solenoid and the valve remains in the activated position until the solenoid is pulsed again to close or deactivate. Constant electrical power is not required to maintain the valve in the activated position due to a mechanical or hydraulic detent which keeps the valve in the last position. In the fail-safe methodology, the valve is pulse activated and will remain open until the supply pressure drops below a specific value or the solenoid is pulsed again. This type of valve is typically used in conjunction with the pulse activated last position type valve as a fail safe measure. The failsafe portion of the valve is placed upstream of the pulse activating portion of the valve in order to cut off pressure to all functions and block the supply until reactivated. The fail-safe type valve is not usually configured with a coupler outlet interface because it only communicates via the supply line internal the valve module.
The electric power required to operate an electrically-powered actuator for a valve, such as a solenoid valve, is a function of the square of the force required and, therefore, any reduction in the force required to operate the valve will afford significant economics in both the construction and the operation of a solenoid actuated pilot valve. For example, if the force to operate a valve is cut in half, the power consumption is thereby reduced to one-fourth the original amount. A sizable savings by reducing the amount of power required to move a solenoid plunger, both from the standpoint of the cost of the initial installation, subsequent operating cost, and reduced heat build-up which provides for greater reliability. Recognized is the need for a control valve requiring minimal amount of electrical power to be actuated.
The state-of-the-art has found shear-type valves to be highly effective in controlling hydraulic functions such as functions on a sub sea tree. The typical shear-type valve will have at least two opposing shear seals communicating with each other through the gate. One will remain covering the supply port during actuation with the other shuttling from block to covering the function port. This allows the supply pressure to access the function upon actuation. On deactivation the supply pressure is again blocked with the function uncovered and venting inside the valve cavity and vent port. The inherent problem with this configuration is shear seal sliding friction which is induced by the hydraulic pressure. The shear seals must be relatively large in order to cover the supply port in both the actuated and inactivated position. The radial seal around the shear seal encircle a large area which is acted upon by the hydraulic pressure. The net result is high force generated on the shear seal face (multiplied by two) that can require high solenoid force to slide from one position to the other. Several solutions have been derived in the past to combat the result of high seal friction. One solution was to add secondary hydraulic pilots to each valve that move the gate from one position to the other. Another solution was to make the porting in the shear seals very small, so the overall net force on the face is manageable. Yet another solution was to incorporate a very large electrical coil to move the gate. And yet another solution, was a combination of some or all of the above. All of the noted solutions have their own inherent problems which for the most part increase the size and complexity of the whole subsea system, reduce or restrict the flow to the subsea function or both. Thus, there is a need for a compact, less complex, control valve requiring a minimal amount of power to be actuated.
A typical subsea control valve does not contain or have the means to connect directly to the function coupler mounted on a base structure, such as those on a sub sea tree. Typically, this entails using a separate male and female coupler. The associated female coupler is an independent component that is either mounted on the bottom of the removable module or assembled on to the valve using a treaded connection with an o-ring seal. The coupler serves only as a hydraulic connection with the mating male coupler on a module fixed base. These subsea hydraulic couplings are well known in the art. Typically, the couplings consist of a male end and a female end with sealed fluid passageways therebetween. The female coupler typically includes a cylindrical body with a relatively large diameter receiving chamber for slidably engaging the male coupler and a relatively small diameter longitudinal bore at the other end. The small bore facilitates connections to hydraulic lines, while the larger bore seals and slidingly engages the male coupler. The male coupler typically includes a cylindrical portion at one end having an outer diameter approximately equal to the diameter of the receiving chamber in the female coupler. The male coupler also typically includes a connection at its other end to facilitate connection to hydraulic lines. When the male coupler is inserted into the receiving chamber of the female coupler, fluid flow is established between the male and female couplers.
The typical coupling devices include the ability to arrest fluid flow when not in mutual contact. The male and female couplers typically include a poppet valve within a central bore of each coupler. Each poppet valve typically includes a conical valve seal which seats, in the closed position, against a valve seat in the bore of each coupler. The poppet valve is engaged by the opposing coupler""s valve actuator and opens to allow fluid flow. The poppet valve closes to arrest fluid flow against a valve seat within the bore. Typically, the poppet valve is spring-biased to the closed position. The valve actuator typically includes a nose or stem extending from the apex of the valve seal along the longitudinal axis of the poppet valve. Engagement between the valve actuators of the male and female coupler""s poppet valves forces each valve face away from the valve seat and into the open position for fluid flow between the couplers. Additional coupling devices typically, the male couplers and female couplers, are attached to opposing manifold plates, whereby in emergency situations, the manifold plate can be quickly separated from the sub sea function, a subsea tree, for example, disconnecting the male and female couplers. Having both male and female couplers as separate units adds to the complexity and size of the valve module. Recognized is that eliminating the need for hydraulic conduit or passageways from the valve to the hydraulic coupler can result in reduced costs and complexity, increased reliability because as many as two seals per circuit can be eliminated by combining the two components into one. There exists, therefore, the need for a coupling assembly integral or part of the control valve.
The typical subsea control valve arrangement includes some form of external valve packaging. The most prevalent packaging methodology includes, but is not limited to some basic options such as: the controlled environment, and the non-controlled environment. In the controlled environment, the valve is typically enclosed in a dielectric fluid filled chamber or module which is typically pressure compensated to mirror that of the surrounding sea water head. A typical subsea control valve is filly enclosed in this chamber and communicates hydraulically to the subsea function via conduit passages to an external mounted hydraulic coupler. The improved valve extends outward from the chamber to directly contact and communicate with the male couplers on the fixed base and will have an environmental seal to separate the chambered fluid from the sea water. It is common for both the hydraulic supply and vent to be routed to a manifold in this configuration. In the non-controlled environment, the valve housing is typically in direct contact with the sea water. The electronics are accessed using conductors placed in a fluid filled hose which in turn typically pressure compensates the electronics section of the valve. No chamber environment seal is required for this configuration. It is common to vent the hydraulic fluid inside the module in this configuration.
A typical control valve will also have an external port tapped into the function output where an independent pressure switch or pressure transmitter is installed at the module assembly. The switch or transmitter may also be threaded and sealed onto the function passage of a manifold between the valve and the output coupler. This configuration is adequate for a controlled environment as previously described; however, it is not adequate for the non-controlled environment where sea water is in direct contact with the module components. Because of the switch location, a second fluid filled hose must be used to protect all of the conductors, one for the solenoid coil, and one for the pressure switch or transmitter. In a module that contains several valves the complexity and cost of two fluid filled hoses per valve may be prohibitive. Recognized, therefore, is the need to place the pressure transmitter conductors coincident with the solenoid conductors. Correspondingly, recognized is the need to route all conductors through a single fitting and into a single pressure compensated, fluid filled hose to the module electrical interface.
In accordance with the invention, an embodiment of the present invention advantageously provides a control valve having a lower cost than valve typically used in oil and gas well control that can be tailored for any number of applications, and which reduces the subsea complexity of its implementation, thus making the system more reliable and user friendly. An embodiment of the present invention advantageously provides a hydraulic control valve having a valve body. The valve body has a function port which may fluidly interface with the hydraulic functions, a supply port to allow for the supply of fluid to the function port, and a vent port to allow fluid to vent from the function port. The hydraulic control valve also includes a valve actuation assembly. The valve actuation assembly includes a plunger for moving a gate assembly between an supply port blocked position and a vent port blocked position. The hydraulic control valve gate assembly includes a gate. The gate slidably interfaces with a seal assembly. The seal assembly includes a seal carrier slidably mounted within the gate and a shear seal to selectably direct hydraulic pressure to and from the subsea function by selectably alternating between a vent open-supply blocked position and a vent closed-supply unblocked position. The shear seal is slidably mounted within the seal carrier. In the preferred embodiment, the configuration may only include one shear seal for scaling of the supply port and the vent port. Using only one shear seal results in relatively low power requirements need to move the shear seal. The seal assembly may also include a seal carrier return spring. The seal carrier return spring connects between the seal carrier and the gate. The hydraulic control valve may also include a roller bearings assembly having roller bearing engagement plate and an array of roller bearings rollingly interfaced with the roller bearing engagement plate.
In an embodiment of the present invention, the hydraulic control valve may further include a valve actuation assembly housing enclosing the valve actuation assembly, a pressure housing enclosing the seal assembly and a spring housing enclosing a gate return spring assembly and a function coupler assembly. The hydraulic control valve further may include a hydraulic pressure coupling assembly having a seal disk hydraulically connected to hydraulic lines.
In an embodiment of the present invention, the hydraulic control valve may further include an internal valve cavity used as both a pressure and a vent chamber, depending upon the valve position. In an embodiment, the control valve may also include a pressure transmitter integral to the valve and in hydraulic communication with the internal valve cavity. In an embodiment, the hydraulic control valve includes a conductor aperture which allows conductors to exit the valve body, and a conductor arrangement wherein a position of the pressure transmitter allows for routing electrically conductive pressure transmitter conductors and electrically conductive actuating conductors through the same conductor aperture.
In an embodiment, the hydraulic control valve may further include a gate return spring assembly. The gate return spring assembly may include a gate return spring having a proximal and distal end, and a spring adapter. The gate return spring is connected to the spring housing on the distal end and the spring adapter is connected to the gate return spring, wherein the gate return spring assembly returns the gate to the vent open-supply blocked position when the actuating assembly is not energized.
In an embodiment, the hydraulic control valve may include a function coupler interface assembly integral with the control valve. The function coupler interface assembly may include a female mating hydraulic coupler assembly for matingly connecting with a male coupling associated with the fixed module base. Additionally, in a controlled environment embodiment, the hydraulic control valve further comprises an environmental scat positioned to seal between the spring housing and the mounting or manifold plate.
An embodiment of the present invention also advantageously provides a hydraulic control valve system, including a hydraulic control valve, a hydraulic removable mounting module, and a mounting assembly. The hydraulic control valve has a valve body, the body having a function port, a supply port to allow for the supply of fluid to the function port, and a vent port to allow fluid to vent from the function port. The control valve may also has a gate assembly, the gate assembly having a gate, a seal assembly, and a roller assembly including a roller bearing engagement plate and an array of roller bearings rollingly interfaced with the roller bearing engagement plate. The seal assembly may include a seal carrier slidably mounted within the gate and a shear seal, to selectively direct hydraulic pressure to and from the subsea function by selectively alternating between a vent open-supply blocked position and a vent closed-supply unblocked position. In the preferred embodiment, the configuration may only include one shear seal for sealing of the supply port and the vent port. The hydraulic control valve may also include an actuation assembly for slidably moving the seal assembly. In the preferred embodiment, the actuation assembly of the valves may include a solenoid assembly.
In the preferred embodiment, the control valve of the hydraulic control valve system may also include a female coupling assembly formed integral with the hydraulic control valve body. This arrangement advantageously reduces the complexity and size of the valve module by eliminating the need for a hydraulic conduit, or manifold, passages from the hydraulic control valve to the hydraulic coupler. Advantageously, the cost of the hydraulic control valve and female coupler can be reduced because they are one integral component. Advantageously, the hydraulic control valve system becomes more reliable because as many as two seals per circuit are eliminated by combining the two components. Additionally, this arrangement advantageously provides fluid pressure communication between the function output passage and the valve cavity. In the preferred embodiment, a pressure switch or transmitter may be made integral with the valve.
The hydraulic control valve system may also include the removable hydraulic mounting module. The mounting module includes the control valve, an input-output module to interface the module to the control valve actuation assembly, and the mounting module housing. In an embodiment, the input-output module may include a program logic controller to selectively control individual valve position. In the preferred embodiment, the mounting module housing may be filled with a dielectric fluid which is in fluid communication with a pressure transmitter chamber.
The hydraulic control valve system may also include the mounting assembly, either separate or as a part of the removable module. The mounting assembly may include a valve retainer for connecting the valve to the mounting module, and an engagement assembly. The engagement assembly connects the module to the fixed base having a function coupler. The engagement assembly may compensate for a separation force generated by supply pressure between the valve and the function coupler. In the preferred embodiment, the engagement assembly includes a latch assembly to releasably latch the removable hydraulic module to the fixed base.
In the preferred embodiment, the hydraulic control valve system may include a plurality of control valves placed in a pattern inside the mounting module housing as to connect them directly to the mating hydraulic couplers on the fixed base, without the need for an additional interface manifold. Correspondingly, in this embodiment, the fixed base side of the mounting module housing may have at least as many apertures, or bores, that allow the distal end of the control valve to protrude from, and be removably engaged with, the fixed base side of the mounting module housing. Additionally, the hydraulic control valve system configured in the control environment arrangement may include an environmental seal for each control valve to provide a seal interface between the control valve and the fixed base side of the mounting module housing. Note, in this embodiment, the fixed base includes an array of male couplers.
An embodiment of the present invention advantageously provides a method for assembling a hydraulic control valve. The method may include the steps of inserting a gate assembly through an open end of a pressure housing, and attaching a seal disk through an aperture, or bore, in the pressure housing to interface with a shear seal. In an embodiment, the gate assembly may include a roller bearing assembly, a gate, a seal carrier, a sealed carrier return spring connected between the gate, and a shear seal. In an embodiment, the method may include the steps of connecting a distal end of the pressure housing with the proximal end of the spring housing so as the gate assembly touchingly engages a spring adapter located within the spring housing. In an embodiment, the method further includes connecting a nonmagnetically responsive tube to the proximal end of the pressure housing, the tube guidingly supporting a solenoid plunger. In an embodiment, the method further includes connecting a solenoid housing to the proximal end of the pressure housing. In an embodiment, the method including connecting a pressure transducer and a pressure transducer cap to the proximal end of the nonmagnetic steel tube to allow a sealed exit for a pressure transducer conductor. An embodiment also includes connecting a proximal end of a spring housing to the distal end of the pressure housing.
A method for assembling a hydraulic control valve system, which includes a control valve having a distal end, includes the steps of providing a hydraulic control valve mounting module housing having at least one aperture, or bore, for receiving a hydraulic control valve body, inserting the distal end of the control valve through the at least one aperture; and connecting the valve retainer to secure the hydraulic control valve body to the module housing. The hydraulic control valve body may be adapted to receive a valve retainer, such as a nut or rim. The valve retainer is used to secure the hydraulic control valve to the control valve mounting module housing. In an embodiment, the valve retainer is threadedly secured to the gate return spring housing.